Windows error loading after Yosemite upgrade

You seem to have a problem similar to other Yosemite upgraders. Are you comfortable using Testdisk and usingBoot Camp won't start after OSX Yosemite upgrade as a reference on how to proceed?

Please post the output of

sudo dd if=/dev/rdisk0s4 count=1 2>/dev/null | hexdump -C

to check if the current partition is NTFS or not?

Your NTFS header is some where above the GPT#4 entry.

Based on your screen shots, your NTFS partition starts at 86923264 and ends at 538218489, since you can see files. I am a bit surprised that you show the NTFS header where your current GPT#4 is (which may be you NTFS backup).

This is what I suggest. Start at Bootcamp missing after expanding partition . Once you are comfortable reading it, then the basic steps are repeated below. Please stop if you see any error messages.

1. Delete the old entry and create a new entry at GPT#4.

sudo gdisk /dev/disk0

p

d

4

n

4

86923264

538218489

0700

p

w

y

2. You will need to reboot after the change, because the disk you are booted from is the one being modified. Reboot will rebuild disk0s4 using the start/end you entered.

3. Run the dd command - sudo dd if=/dev/rdisk0s4 count=1 2>/dev/null | hexdump -C and check that the first line contains "R.NTFS".

4. This is a tedious process and you want to check after the second 'p'rint command that it looks reasonable, before the 'w'rite and 'y'es to confirm.

5. Once you a working GPT#4, a new hybrid MBR needs to be created which will overwrite what you see in your Fdisk output. This is also done using GPT Fdisk (Gdisk).

6. a. Test 1 - Can you see your Bootcamp volume in Finder.

b. Test 2 - Can you files in the Bootcamp volume?

c. Test 3 - Can you see Bootcamp in your System Preferences -> Startup Disk.

d. Test 4 - If Test 1-3 are successful, select Bootcamp and click on Restart. You may need Windows startup repair, if you see a hanging underline cursor at the top left corner of your screen. In most cases, it is not required.

Here is an example...

Command (? for help): d

Partition number (1-4): 4

Command (? for help): n

Partition number (4-128, default 4): 4

First sector (34-1954210086, default = 1454210080) or {+-}size{KMGTP}: 1454211072

Last sector (1454211072-1954210086, default = 1954210086) or {+-}size{KMGTP}: 1954209791

Current type is 'Apple HFS/HFS+'

Hex code or GUID (L to show codes, Enter = AF00): 0700

Changed type of partition to 'Microsoft basic data'

Command (? for help): p

Disk /dev/disk0: 1954210120 sectors, 931.8 GiB

Logical sector size: 512 bytes

Disk identifier (GUID): 6ED0C429-00D1-4759-B50E-04B6FB80D0E3

Partition table holds up to 128 entries

First usable sector is 34, last usable sector is 1954210086

Partitions will be aligned on 8-sector boundaries

Total free space is 1293 sectors (646.5 KiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 1452940543 692.6 GiB AF00 Customer

3 1452940544 1454210079 619.9 MiB AB00 Recovery HD

4 1454211072 1954209791 238.4 GiB 0700 Microsoft basic data

Can you look at this link - http://support.microsoft.com/kb/927392?

You may need to recreate your BCD data. Your disk is an MBR disk, it should be GPT with a Hybrid MBR.

One issue that I have seen in the past is if the disk does not have an EFI, the CSM-BIOS layer also has issues and causes a mismatch between the devices that Windows thinks it has and can cause startup issues.

Can you re-create GPT#1 (EFI/ESP)? Please backup your current GPT with Gdisk, before you make any further changes so you have a backup of this working one.

Thanks for this post, I will try to follow this one and see if it works.

1. Please take a backup of your current GPT before making changes using the 'b' option in Gdisk and put it on an external flash drive for safekeeping.

2. You currently do not have a GPT#1. This may work. If you get an error, please stop and post back.

sudo gdisk /dev/disk0

n

1

40

409600

EF00

p

w

y

Reboot.

Please test OSX boot, and make sure your volumes show up correctly. If everything works normally on the OSX side, try to switch to Bootcamp.

If this works, I will be very thrilled. 😉

1. GPT#1 looks a bit strange. it should end on 409600. This may be due to Gdisk using alignment.

2. Does bootrec.exe allow /fixmbr? /scanos may not be able to detect an OS till the MBR gets fixed.

3. You always have hope. 😉